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Resource.javaAPI DocExample5655Fri Feb 21 13:11:42 GMT 2003None

Resource

public class Resource extends Object implements Serializable
A class to locate resources, retrieve their contents, and determine their last modified time. To find the resource the class searches the CLASSPATH first, then Resource.class.getResource("/" + name). If the Resource finds a "file:" URL then the file path will be treated as a file. Otherwise the path is treated as a URL and has limited last modified info.

Fields Summary
private String
name
private File
file
private URL
url
Constructors Summary
public Resource(String name)

    this.name = name;
    SecurityException exception = null;

    try {
      // Search using the CLASSPATH.  If found, "file" is set and the call
      // returns true.  A SecurityException may bubble up.
      if (tryClasspath(name)) {
        return;
      }
    }
    catch (SecurityException e) {
      exception = e;  // save for later
    }

    try {
      // Search using the class loader getResource().  If found as a file,
      // "file" is set, if found as a URL then "url" is set.
      if (tryLoader(name)) {
        return;
      }
    }
    catch (SecurityException e) {
      exception = e;  // save for later
    }

    // If we get here we failed, report the exception
    String msg = "";
    if (exception != null) {
      msg = ": " + exception;
    }

    throw new IOException("Resource '" + name + "' could not be found in " +
      "the CLASSPATH (" + System.getProperty("java.class.path") +
      "), nor could it be located by the classloader responsible for the " +
      "web application (WEB-INF/classes)" + msg);
Methods Summary
public java.lang.StringgetDirectory()
Returns the directory containing the resource, or null if the resource isn't directly available on the filesystem. This value can be used to locate the config file on disk or write files in the same directory.

    if (file != null) {
      return file.getParent();
    }
    else if (url != null) {
      return null;
    }
    return null;
public java.io.InputStreamgetInputStream()
Returns an input stream to read the resource contents.

    if (file != null) {
      return new BufferedInputStream(new FileInputStream(file));
    }
    else if (url != null) {
      return new BufferedInputStream(url.openStream());
    }
    return null;
public java.lang.StringgetName()
Returns the resource name, as passed to the constructor.

    return name;
public longlastModified()
Returns when the resource was last modified. If the resource was found using a URL, this method will only work if the URL connection supports last modified information. If there's no support, Long.MAX_VALUE is returned. Perhaps this should return -1 but we return MAX_VALUE on the assumption that if you can't determine the time, assume it's maximally new.

    if (file != null) {
      return file.lastModified();
    }
    else if (url != null) {
      try {
        return url.openConnection().getLastModified();  // hail mary
      }
      catch (IOException e) { return Long.MAX_VALUE; }
    }
    return 0;  // can't happen
private static java.io.FilesearchDirectories(java.lang.String[] paths, java.lang.String filename)

    SecurityException exception = null;
    for (int i = 0; i < paths.length; i++) {
      try {
        File file = new File(paths[i], filename);
        if (file.exists() && !file.isDirectory()) {
          return file;
        }
      }
      catch (SecurityException e) {
        // Security exceptions can usually be ignored, but if all attempts
        // to find the file fail, then report the (last) security exception.
        exception = e;
      }
    }
    // Couldn't find any match
    if (exception != null) {
      throw exception;
    }
    else {
      return null;
    }
private static java.lang.String[]split(java.lang.String str, java.lang.String delim)

    // Use a Vector to hold the splittee strings
    Vector v = new Vector();

    // Use a StringTokenizer to do the splitting
    StringTokenizer tokenizer = new StringTokenizer(str, delim);
    while (tokenizer.hasMoreTokens()) {
      v.addElement(tokenizer.nextToken());
    }

    String[] ret = new String[v.size()];
    v.copyInto(ret);
    return ret;
public java.lang.StringtoString()

    return "[Resource: File: " + file + " URL: " + url + "]";
private booleantryClasspath(java.lang.String filename)

    String classpath = System.getProperty("java.class.path");
    String[] paths = split(classpath, File.pathSeparator);
    file = searchDirectories(paths, filename);
    return (file != null);
private booleantryLoader(java.lang.String name)

    name = "/" + name;
    URL res = Resource.class.getResource(name);
    if (res == null) {
      return false;
    }

    // Try converting from a URL to a File
    File resFile = urlToFile(res);
    if (resFile != null) {
      file = resFile;
    }
    else {
      url = res;
    }
    return true;
private static java.io.FileurlToFile(java.net.URL res)

    String externalForm = res.toExternalForm();
    if (externalForm.startsWith("file:")) {
      return new File(externalForm.substring(5));
    }
    return null;